About LM7805 voltage regulator IC:
It is a fixed linear voltage regulator IC which is member of the 78xx series. When the applied voltage is between 7-24 v it gives a constant output of voltage of 5 volts. It can only be used as a buck converter which can power low powered devices.
Pin diagram of LM7805 Voltage regulator
- Input voltage: 7v to 25v
- Output voltage range: 4.8 v to 5.2v
- Typical output voltage: 5v
- Maximum output current: 1.5A
Components Need for this project
- LM7805 Voltage Regulator IC
- Transformer: Any whose output is between 9-24 volts
- Capacitors: 10uF(2)
- Diode: 1n4007(4)
How Circuit works
Ac Voltage of 220-240 volts is applied to the transformer which then step-down it to 9 volts. After that 9v AC voltage is fed to the full-wave bridge rectifier which converts the AC signal in DC signal. The DC voltage which we get from the output of the bridge rectifier is not true DC, to make it ripple-free we use a capacitor of 100uf 16volts as h AC filter. Then using LM7805 we further stepdown the 9 volts to 5 volts. After that one 10uf 16 volts capacitor is also added to remove all the AC components left in 5 volts DC.
- Always choose a transformer whose output voltage is greater than the minimum voltage required for the voltage regulator to work.
- While choosing a capacitor you have to keep in mind that the voltage rating on the capacitor must be double than the output voltage from the diode and output voltage from the voltage regulator respectively.